On Thursday, Buchannon, 39, pleaded guilty to malice murder and several other felony charges in Gordon County Superior Court. Judge David Smith then sentenced Buchannon to life in prison without the possibility of parole. He also was sentenced to 91 years in prison in addition to the life sentence.

Cherokee Judicial Circuit District Attorney Joe Campbell said he's thankful McKnight's family didn't have to go through a trial. But he refused to offer a lesser plea bargain for Buchannon because of the nature of his "egregious" crimes.

"I wanted each victim respected and recognized by a separate type of sentence," he said.

Buchannon was charged last July with the kidnapping and death of 40-year-old Christy McKnight, whose dead body was found sprawled on railroad tracks several miles from her home in Resaca, Ga.

He also was charged with two counts of aggravated assault for shooting McKnight's 17-year-old son ,Dustin Henderson, and her nephew, 19-year-old Cody Adams. Neither died.

Buchannon's trial was slated to start Monday, but at the last minute he decided to plead guilty, Dettmar said.

"He decided to take responsibility for his actions," the attorney said.

Campbell contends that Buchannon had only dated McKnight for a few weeks in July when he told her he wanted to live together, but she refused and stopped seeing him. Driven by obsession, Buchannon tried to win her back with flowers and phone calls, Campbell said, but when McKnight finally told him she was dating someone else, Buchannon snapped.

Buchannon drove back to his temporary home at the Royal Inn Motel in Calhoun, Ga., stole a neighbor's 9mm handgun from the bed of a truck and went back to Mc-Knight's home, Campbell said. Bursting through the door, Buchannon demanded McKnight go with him, then shot her son and nephew to prove he was serious, Campbell said. McKnight reluctantly went with Buchannon.

Buchannon parked McKnight's Camaro and dragged her onto abandoned railroad tracks off U.S. Highway 41, Campbell said. With the last bullet from his stolen gun, Buchannon shot McKnight execution style in the back of the head, he said.

"It's a crime of obsession," Campbell said. "He just couldn't let her go."

While Buchannon admitted to the crimes, he argued he killed McKnight only after a struggle over the gun, Dettmar said.

Buchannon was arrested after an officer shot him. Even then, Buchannon pointed his empty gun at the officers and refused to surrender, police said.